\section*{Notations}
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	\begin{table}[H]%[htbp]表格参数设置，固定位置
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		\caption{Some notations}
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				$s$                       &user number\\
				$t$                       &item number\\
				$k$                       &latent dimension (category number)\\
                $U,Y^u \in \mathbb{R}^{s\times k}$        &user latent matrix\\
				$V,Y^v \in \mathbb{R}^{t\times k} $       &item latent matrix \\
				$X \in \mathbb{R}^{t\times k}$            &ranking scores under categories\\
				$x_c \in X$                     &ranking score vector under category $c$\\
				$y^v_{*,c} \in Y^v$             & c-th column of $Y^v$\\
				$L\in \mathbb{R}^{t\times k}$   &ranking lists under categories\\
				$\rho \in \mathbb{R}^k$         & counters of category popularity\\
				$e \in \{u,v\}$                 & entity\\
				$A^e$                           &content feature of entities\\
				$W^e$                           &mapping matrix\\
				$Y^e$                           &entity latent matrix\\
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			\end{tabular}
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	\end{table}
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